Most misdemeanors don't just automatically go away after 7 years or after any period of time and the misdemeanor will usually stay on your record for life.
But after 3 to 5 years you can fill out a Motion To Vacate form and see a judge to have the misdemeanor conviction removed from your record.
Your record must remain clean and have no other convictions on it within those 3 to 5 years when you file the motion to vacate the misdemeanor form.